1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly to a method of fabricating electrodes of plasma display panel using a photo-peeling method, which can make the electrode highly precise in correspondence to high resolution. Further, the present invention relates to a method of fabricating electrodes of plasma display panel using a photo-peeling method that is environment-friendly, with which it is easy to recycle materials and that is capable of reducing cost when forming the electrodes of the plasma display panel.
2. Description of the Related Art
A plasma display panel (hereinafter, PDP) displays a picture by exciting phosphorus to emit light ultraviolet ray generated when an inert mixture gas such as He+Xe, Ne+Xe, or He+Xe+Ne discharges electricity. The PDP can not only be easily made into a thinner and high definition large-scaled screen, but also improves in its quality due to the recent technology development.
Ref erring to FIG. 1, a discharge cell of three electrode AC surface discharge PDP includes a pair of sustain electrodes having a scan electrode Y and a sustain electrode Z formed on an upper substrate 1, and an address electrode X formed on a lower substrate 2 crossing the sustain electrode pair perpendicularly. Each of the scan electrode Y and the sustain electrode Z includes a transparent electrode and a metal bus electrode formed on top of it. An upper dielectric substance 6 and an MgO protective layer 7 are deposited on the upper substrate 1 provided with the scan electrode Y and the sustain electrode Z. A lower dielectric layer 4 is formed on the lower substrate 2 provided with the address electrode X, to cover the address electrode X. Barrier ribs 3 are perpendicularly formed on the lower dielectric layer 4. Phosphorus 5 is formed on the surface of the lower dielectric layer 4 and the barrier ribs 3. An inert mixture gas, such as He+Xe, Ne+Xe, or He+Xe+Ne, is injected into a discharge space provided between the upper substrate 1 and the lower substrate 2 and the barrier ribs 3. The upper substrate 1 and the lower substrate 2 are bonded together by a sealant (not shown).
Scan signals are applied to the scan electrode Y to select scan lines. And sustain signals are alternately applied to the scan electrode Y and the sustain electrode Z to maintain the discharge of the selected cells. Data signals are applied to the address electrode X to select cells.
The metal bus electrode of the scan electrode Y and the sustain electrode Z needs to have its width as narrow as it can be within the scope where line resistance is not too much high because it intercepts light from phosphorus to deteriorate brightness as much. Such a metal bus electrode is made by depositing a metal layer with three-layered structure of Cr/Cu/Cr on the transparent electrode by a vacuum deposition method and then patterning the metal layer by photolithography and etching process.
The address electrode X is formed on the lower substrate 2 by a pattern print method where silver Ag paste is printed on the lower substrate 2 through a screen after the screen for patterning is printed on the lower substrate 2, or by a photo method including photolithography and etching process after the silver paste is printed on the lower substrate 2.
However, there is the following problem with the pattern print method and photo method. The pattern print method has an advantage in that the process is relatively simple and the metal electrode can be formed at low cost, but it has two disadvantages. First, it is difficult to use the method for large size and high precision which are required for high resolution of PDP because the electrode width cannot be smaller than a given limit. Second, material such as volatile solvent, which is harmful to humans, has to be used because the material has to be in a state of paste. When compared to this, the photo method has an advantage in that it can be applied to large size and high precision because a relatively small electrode pattern can be formed, but it too has two disadvantages. First, it is not environment-friendly because the material is in the state of paste, and, second, the material is wasted and its cost is high because the entire surface of the substrate has to be printed with the material in paste.
Accordingly, it is an object of the present invention to provide a method of fabricating electrodes of PDP using a photo peeling method, by which the electrode can be made highly precise according to high resolution.
It is another object of the present invention to provide a method of fabricating electrodes of PDP using a photo peeling method that is environment-friendly, with which it is easy to recycle materials and that is capable of reducing cost when forming the electrodes of the plasma display panel.
In order to achieve these and other objects of the invention, a method of fabricating an electrode of a plasma display panel using a photo peeling method according to an aspect of the present invention includes the steps of forming a photo material layer on a substrate, wherein the adhesive strength of the photo material layer decreases when the photo material is exposed to light; exposing the photo material layer to light according to a desired pattern; forming an electrode material layer on the exposed and unexposed areas of the photo material layer; forming a peeling material layer on the electrode material layer, wherein the peeling material layer has higher adhesive strength for the electrode material than area of the photo material layer has for the electrode material; and the peeling material layer to leave the desired pattern of the electrode material layer on the unexposed areas of the photo material layer.
In the method, the exposed area of the electrode material layer is removed when removing the peeling material layer.
The method further includes the step of firing the remaining area except where the electrode material layer was removed by the peeling material layer.
The photo material layer includes binder of 20˜50 wt %; reactive monomer of 40˜70 wt %; photo initiator of 2˜5 qt %; and additive of 2˜5 wt %.
In the method, the binder includes at least one of polyurethane, polyester, polyacrylate, co-polymer with carboxylic -COOH and radical OH or tri-polymer with carboxylic -COOH and radical OH.
In the method, the reactive monomer includes at least one of a multi-functional monomer with 2˜5 reactive radicals, acrylic monomer or urethane monomer and oligomer.
In the method, the photo initiator includes at least one of 1-hydroxy-cyclochexyl-phenyl ketone, p-pheny benzo phenone, benzyldimethylketal, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isobutyl ether, 4,4′ diethylaminobenzo-phenone, p-dimethyl amino benzoic acid ethylester.
In the method, the additive includes at least one of dispersing agent, stabilizer and polymerization prohibiting agent.
The electrode material layer includes silver Ag powder of 90˜99 wt %; and glass-frit of 1˜10 wt %.
The peeling material layer includes binder of 70˜80 wt %; and additive of 20˜30 wt %.
In the method, the binder includes at least one of polyurethane, polyester, polyacrylate, co-polymer with radical OH or tri-polymer with radical OH.
In the method, the additive includes at least one of dispersing agent, stabilizer and polymerization prohibiting agent.